Enum WidthMode 

pub enum WidthMode {
    Wc,
    Grapheme,
}

How grapheme clusters are measured for terminal-cell layout.

This enum does not control segmentation: grapheme_cells always segments by extended grapheme cluster. It controls only width calculation for each cluster. The East-Asian Ambiguous policy is orthogonal and is passed as a separate eaw_wide boolean to char_width and grapheme_width.

Variants

Wc

Measure each cluster by summing the widths of its code points.

This models a terminal that has no grapheme segmentation and advances the cursor once per code point, which is what POSIX wcswidth describes: the sum of wcwidth over the string. Combining marks, joiners, and variation selectors are themselves zero-width, so they add nothing and a cluster like e + combining acute still measures one cell. A code point that owns cells does add, which is why a regional-indicator pair measures two.

A long joined sequence measures the sum of its parts, so a four-person family emoji is eight columns and a skin-toned thumbs-up is four. Use this when matching older or simpler terminal width behavior is more important than cluster-aware emoji presentation.

Grapheme

Measure the whole grapheme cluster.

This mode accounts for variation selectors, regional indicators, zero-width-joiner sequences, and pictographic presentation when deciding whether a cluster occupies zero, one, or two cells. Use it for modern terminal rendering that treats emoji and joined clusters as a single displayed unit.

Implementations

impl WidthMode

pub fn grapheme_width(self, g: &str, eaw_wide: bool) -> u8

Measure one extended grapheme cluster under this mode.

In WidthMode::Wc mode, the width is the sum of char_width over every code point in g; an empty string is 0. In WidthMode::Grapheme mode, the width is grapheme_width for the whole cluster.

Parameters

• g — an extended grapheme cluster. Passing a longer string is accepted, and in Wc mode every code point in it counts toward the sum.
• eaw_wide — East-Asian Ambiguous policy; see char_width.

Returns

The cluster width in terminal cells. WidthMode::Grapheme returns 0, 1, or 2; WidthMode::Wc sums code points and can return more, saturating at u8::MAX.

Errors and panics

This method does not fail or intentionally panic.

Trait Implementations

impl Clone for WidthMode

fn clone(&self) -> WidthMode

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for WidthMode

impl Debug for WidthMode

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for WidthMode

fn default() -> WidthMode

Returns the “default value” for a type.

impl Eq for WidthMode

impl Hash for WidthMode

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for WidthMode

fn eq(&self, other: &WidthMode) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for WidthMode